Test key pad structure and its layout design method
Patent Information
- Application Number
- CN202610628439.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-08
- Publication Date
- 2026-09-01
AI Technical Summary
[0031] This invention, by further setting a mesh-like interlaced structure in the block area of the test key pad, can prevent the metal of the test key pad from developing a butterfly-shaped depression while ensuring that the area block size of the test key pad meets the requirements. This can increase the contact area between the probe and the metal of the test key pad in WAT testing, thereby improving the accuracy of WAT testing, and also increasing the bonding contact area to prevent bonding failure.
Smart Images
Figure CN122679880A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor integrated circuit manufacturing, and in particular to a test key (TSK) pad (PAD) structure. The invention also relates to a layout design method for the test key pad. Background Technology
[0002] Because the wafer acceptance test (WAT) TSK PAD uses a large solid metal such as Cu, which is softer than the surrounding dielectric material, the metal is more easily removed by the polishing pad and polishing fluid during the CMP stage, resulting in dishing defects in the metal Cu. This leads to problems such as inaccurate WAT tests and bonding failure.
[0003] like Figure 1 The diagram shown is a top view of an existing test key pad structure; the test key pad 101 has a large solid metal block 102. Figure 2 The diagram shown is a cross-sectional view of an existing test key pad structure. Because the solid metal block 102 of the test key pad 101 has a large area and is softer than the dielectric material corresponding to the surrounding interlayer film 103, a butterfly-shaped defect 105 will form after CMP. A bottom metal layer pattern 104 is formed at the bottom of the test key pad 101.
[0004] like Figure 3 As shown, is Figure 2 The diagram shows the connection between the existing test key pad structure and the probe during WAT testing. During WAT testing, the probe 106 needs to make metal contact with the test key pad 101. It can be seen that due to the presence of the butterfly defect 105, the contact area will be reduced, which will result in inaccurate test results.
[0005] like Figure 4 The diagram shown is a schematic of the device structure after bonding using the existing test bond pad structure. Figure 5 yes Figure 4 Enlarged view of the middle frame at point 206; as shown Figure 4 The diagram shown is a schematic of the device structure after bonding using the existing test bond pad structure. Figure 4The diagram shows a schematic of the structure of a CMOS sensor after a pixel chip 201 and a logic chip 202 are hybrid bonded (HB) through a frame 205. The pixel chip 201 is formed on a semiconductor substrate 203a, and a metal interconnect structure 204a is formed on the front side of the semiconductor substrate 203a. The logic chip 202 is formed on a semiconductor substrate 203b, and a metal interconnect structure 204b is formed on the front side of the semiconductor substrate 203b. In the hybrid bonding, the test bond pads 101 on the top layers of the two semiconductor substrates corresponding to the frame 206 are bonded together. Because the existing metal top surface of the test bond pads 101 has a butterfly-shaped defect 105, therefore... Figure 5 This will create a gap 207. Figure 5 In the diagram, the corresponding test key pads in pixel chip 201 and logic chip 202 are labeled 101a and 101b, respectively, and the interlayer films are labeled 103a and 103b, respectively. Summary of the Invention
[0006] The technical problem to be solved by this invention is to provide a test key pad structure that prevents butterfly-shaped indentations in the metal of the test key pad while ensuring the required area size. This increases the contact area between the probe and the metal of the test key pad during WAT testing, thereby improving the accuracy of WAT testing. It also increases the bonding contact area and prevents bonding failure. To this end, this invention provides a layout design method for the test key pad.
[0007] To solve the above-mentioned technical problems, the test key pad structure provided by the present invention has a block structure in the forming area of the test key pad.
[0008] Within the forming area of the test key pad, the test key pad has a mesh-like interlaced structure. The mesh-like interlaced structure divides the metal within the forming area of the test key pad into multiple interconnected metal segment patterns. The width of each metal segment pattern is smaller than the width of the block structure, and the width of each metal segment pattern is set to meet the requirement that the metal of the test key pad does not undergo butterfly-shaped indentation.
[0009] A further improvement is that the mesh-like interlaced structure is defined by the layout pattern of the test key pads, the layout pattern of which includes: A first pattern array formed by multiple parallel first stripes extending in a first direction.
[0010] A second pattern array formed by multiple parallel stripes extending in a second direction.
[0011] The first direction and the second direction are perpendicular, and the mesh-like interlaced structure is formed by the intersection of the first pattern array and the second pattern array. Each of the metal segmentation patterns is composed of the corresponding first strip or the second strip.
[0012] A further improvement is that an interlayer film is formed in the regions between each of the metal segmentation patterns.
[0013] A further improvement is that the metal of each of the said metal segmentation patterns includes copper.
[0014] A further improvement is that the top view of the block structure is square.
[0015] A further improvement is that the width of each of the first strips is the same as the width of each of the second strips, and the spacing between each of the first strips is the same as the spacing between each of the second strips.
[0016] A further improvement is that a metal ring structure is also provided on the periphery of the mesh-like interlaced structure.
[0017] Both ends of each of the first strips and each of the second strips are connected to the metal ring structure.
[0018] To solve the above technical problems, the present invention provides a layout design method for test key pads, comprising: the forming area of the test key pad is a block structure; defining the layout pattern of the test key pad in the layout; the layout pattern of the test key pad having a mesh-like interlaced structure; the mesh-like interlaced structure being located within the forming area of the test key pad; and the mesh-like interlaced structure dividing the metal within the forming area of the test key pad into multiple interconnected metal segmentation patterns.
[0019] The test key pad is fabricated according to the layout definition. Metal is formed at each of the metal segmentation patterns of the test key pad, and an interlayer film is formed between each of the metal segmentation patterns. The process of forming the test key pad also includes CMP to planarize the surface of the metal of the test key pad and the interlayer film outside the metal. The width of each metal segmentation pattern is smaller than the width of the block structure, and the width of each metal segmentation pattern is sufficient to prevent the metal of the test key pad from developing a butterfly-shaped depression during the CMP process.
[0020] A further improvement is that, in the layout, the layout pattern of the test key pad includes: A first pattern array formed by multiple parallel first stripes extending in a first direction.
[0021] A second pattern array formed by multiple parallel stripes extending in a second direction.
[0022] The first direction and the second direction are perpendicular, and the mesh-like interlaced structure is formed by the intersection of the first pattern array and the second pattern array. Each of the metal segmentation patterns is formed by the intersection of the corresponding first stripe and the second stripe.
[0023] A further improvement is that the metal of each of the said metal segmentation patterns includes copper.
[0024] A further improvement is that the top view of the block structure is square.
[0025] A further improvement is that the width of each of the first strips is the same as the width of each of the second strips, and the spacing between each of the first strips is the same as the spacing between each of the second strips.
[0026] A further improvement is that a metal ring structure is also provided on the periphery of the mesh-like interlaced structure.
[0027] Both ends of each of the first strips and each of the second strips are connected to the metal ring structure.
[0028] A further improvement includes providing an initial layout in which a solid block-shaped pattern is provided in the formation area of the test key pad.
[0029] The layout is obtained by replacing the pattern of the test key pad with the pattern of the test key pad having the mesh interlaced structure. This includes replacing the initial layout pattern of the test key pad having the solid block structure pattern in the initial layout with the pattern of the test key pad having the mesh interlaced structure.
[0030] A further improvement is that, after the graphic replacement is completed, the method further includes: performing a layout versus layout (LVL) comparison on the data of the layout and the initial layout.
[0031] This invention, by further setting a mesh-like interlaced structure in the block area of the test key pad, can prevent the metal of the test key pad from developing a butterfly-shaped depression while ensuring that the area block size of the test key pad meets the requirements. This can increase the contact area between the probe and the metal of the test key pad in WAT testing, thereby improving the accuracy of WAT testing, and also increasing the bonding contact area to prevent bonding failure. Attached Figure Description
[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 This is a top view schematic diagram of the existing test key pad structure; Figure 2 This is a cross-sectional schematic diagram of an existing test key pad structure; Figure 3 yes Figure 2 The diagram shows the connection between the existing test key pad structure and the probe during WAT testing. Figure 4 This is a schematic diagram of the device structure after bonding using the existing test bond pad structure; Figure 5 yes Figure 4 Enlarged view of the middle frame at point 206; Figure 6 This is a top view schematic diagram of the test key pad structure according to an embodiment of the present invention; Figure 7 This is the layout pattern of the first pattern array of the test key pad structure in an embodiment of the present invention; Figure 8 This is the layout pattern of the second pattern array of the test key pad structure in an embodiment of the present invention; Figure 9 This is a cross-sectional schematic diagram of the test key pad structure according to an embodiment of the present invention; Figure 10 yes Figure 9 The diagram shown illustrates the connection between the test key pad structure and the probe during WAT testing according to an embodiment of the present invention. Figure 11 This is a schematic diagram of the device structure after bonding using the test bond pad structure of the present invention. Detailed Implementation
[0033] like Figure 6 The diagram shown is a top view of the test key pad 301 structure according to an embodiment of the present invention; as shown... Figure 9 The diagram shown is a cross-sectional view of the test key pad 301 structure according to an embodiment of the present invention. In the test key pad 301 structure of the embodiment of the present invention, the forming area of the test key pad 301 is a block structure.
[0034] In this embodiment of the invention, the top view of the block structure is square. In other embodiments, the top view of the block structure can also be set to other shapes as needed.
[0035] Within the forming area of the test key pad 301, the test key pad 301 has a mesh-like interlaced structure 302. The mesh-like interlaced structure 302 divides the metal within the forming area of the test key pad 301 into multiple interconnected metal segmentation patterns 302c. The width of each metal segmentation pattern 302c is smaller than the width of the block structure, and the width of each metal segmentation pattern 302c is set to meet the requirement that the metal of the test key pad 301 does not undergo butterfly-shaped indentation.
[0036] In this embodiment of the invention, the mesh-like interlaced structure 302 is defined by the layout pattern of the test key pad 301, and the layout pattern of the test key pad 301 includes: like Figure 7 The diagram shows the layout of the first pattern array of the test key pad 301 structure according to an embodiment of the present invention; the first pattern array is formed by multiple first stripes 302a extending in a first direction arranged in parallel.
[0037] like Figure 8 The diagram shows the layout of the second pattern array of the test key pad 301 structure according to an embodiment of the present invention; the second pattern array is formed by multiple parallel arrangement of second strips 302b extending in the second direction.
[0038] The first direction and the second direction are perpendicular, and the pattern of the mesh-like interlaced structure 302 is formed by the intersection of the first pattern array and the second pattern array. Each of the metal segmentation patterns 302c is composed of the corresponding first strip 302a or second strip 302b.
[0039] In this embodiment of the invention, the width of each first stripe 302a is the same as the width of each second stripe 302b, and the spacing between each first stripe 302a is the same as the spacing between each second stripe 302b.
[0040] The periphery of the mesh-like interlaced structure 302 also has a metal ring structure 303.
[0041] In some embodiments, the distance of each side of the mesh-like interlaced structure 302 from the center point is 20 micrometers to 30 micrometers. The width of each first stripe 302a, the width of each second stripe 302b, the spacing between each first stripe 302a, and the spacing between each second stripe 302b are all the same, and the size is 0.5 micrometers to 1.5 micrometers.
[0042] Both ends of each of the first strips 302a and each of the second strips 302b are connected to the metal ring structure 303.
[0043] An interlayer film 304 is formed in the region between each of the metal segmentation patterns 302c.
[0044] The metal in each of the described metal segmentation patterns 302c includes copper. Copper is typically formed using a damascus process, and after electroplating, CMP (Chemical Motion Processing) is usually required for planarization, such as... Figure 9 As shown, in this embodiment of the invention, the width of each metal segmentation pattern 302c is well controlled and is no longer the width of the entire area block of the forming region of the test key pad 301, so CMP will not produce butterfly defects. Figure 9In the process, a bottom metal pattern 305 is also formed at the bottom of the metal segmentation pattern 302c.
[0045] In this embodiment of the invention, by further providing a mesh-like interlaced structure 302 within the blocky area of the test key pad 301, the metal of the test key pad 301 can be prevented from developing a butterfly-shaped indentation while ensuring that the block size of the test key pad 301 meets the requirements. This increases the contact area between the probe and the metal of the test key pad 301 during WAT testing, thereby improving the accuracy of WAT testing. It also increases the bonding contact area and prevents bonding failure.
[0046] like Figure 10 As shown, is Figure 9 The diagram shown is a schematic of the connection between the test key pad structure and the probe during WAT testing according to an embodiment of the present invention. It can be seen that because the surface of the metal segmentation pattern 302c is flat, the probe 306 can form good contact with the metal segmentation pattern 302c, which ultimately makes the test results accurate.
[0047] like Figure 11 The diagram shown is a schematic of the device structure after bonding using the test bond pad structure of the present invention. Figure 11 The diagram shows a schematic of the hybrid bonding structure of a pixel chip 401 and a logic chip 402 in a CMOS sensor, corresponding to frame 405. The pixel chip 401 is formed on a semiconductor substrate 403a, and a metal interconnect structure 404a is formed on the front side of the semiconductor substrate 403a. The logic chip 402 is formed on a semiconductor substrate 403b, and a metal interconnect structure 404b is formed on the front side of the semiconductor substrate 403b. In this hybrid bonding, the test bond pads 301 on the top layers of the two semiconductor substrates are bonded together. Since the metal top surfaces of each region of the test bond pads 301 in this embodiment are flat, no issues such as… Figure 5 The corresponding gap 207 means that the embodiments of the present invention can eliminate the bonding failure problem caused by the existing structure.
[0048] The layout design method for the test key pad 301 in this embodiment of the invention includes: the forming area of the test key pad 301 is a block structure; the layout pattern of the test key pad 301 is defined in the layout; the layout pattern of the test key pad 301 has a mesh-like interlaced structure 302; the mesh-like interlaced structure 302 is located within the forming area of the test key pad 301; the mesh-like interlaced structure 302 divides the metal within the forming area of the test key pad 301 into multiple interconnected metal segmentation patterns 302c.
[0049] The test key pad 301 is fabricated according to the layout definition. Metal is formed at each of the metal segmentation patterns 302c of the test key pad 301, and an interlayer film 304 is provided between each of the metal segmentation patterns 302c. The process of forming the test key pad 301 also includes CMP to planarize the surface of the metal of the test key pad 301 and the surface of the interlayer film 304 outside the metal. The width of each metal segmentation pattern 302c is smaller than the width of the block structure, and the width of each metal segmentation pattern 302c is sufficient to prevent the metal of the test key pad 301 from developing a butterfly-shaped depression during the CMP process.
[0050] In the method of this embodiment, the top view of the block structure is square.
[0051] In the layout, the layout pattern of the test key pad 301 includes: A first pattern array is formed by multiple first stripes 302a extending in the first direction arranged in parallel.
[0052] A second pattern array is formed by multiple parallel arrangement of second stripes 302b extending in the second direction.
[0053] The first direction and the second direction are perpendicular, and the pattern of the mesh-like interlaced structure 302 is formed by the intersection of the first pattern array and the second pattern array. Each of the metal segmentation patterns 302c is formed by the intersection of the corresponding first strip 302a and second strip 302b.
[0054] Preferably, the width of each first stripe 302a and the width of each second stripe 302b are the same, and the spacing between each first stripe 302a and the spacing between each second stripe 302b are the same. In other embodiments, the width of each first stripe 302a and the width of each second stripe 302b can also be set independently as needed, as long as it is ensured that no butterfly-shaped defects will occur after CMP.
[0055] The periphery of the mesh-like interlaced structure 302 also has a metal ring structure 303.
[0056] In some embodiments, the distance of each side of the mesh-like interlaced structure 302 from the center point is 20 micrometers to 30 micrometers. The width of each first stripe 302a, the width of each second stripe 302b, the spacing between each first stripe 302a, and the spacing between each second stripe 302b are all the same, and the size is 0.5 micrometers to 1.5 micrometers.
[0057] The metal in each of the metal segmentation patterns 302c includes copper.
[0058] Both ends of each of the first strips 302a and each of the second strips 302b are connected to the metal ring structure 303.
[0059] The method in this embodiment of the invention further includes: providing an initial layout, wherein the initial layout has a solid block-shaped structure pattern in the forming area of the test key pad 301.
[0060] The layout is obtained by replacing the graphic of the test key pad 301 with the graphic of the test key pad 301 having the mesh interlaced structure 302. The initial layout graphic of the test key pad 301 having a solid block structure graphic is replaced with the graphic of the test key pad 301 having the mesh interlaced structure 302 to obtain the layout.
[0061] After the graphic replacement is completed, the method further includes: performing an LVL comparison on the data of the layout and the initial layout.
[0062] The process then includes: performing a dummy insert using the GDS data of the replaced layout, thereby obtaining the layout graphic of the embodiment of the invention having the test key pad 301.
[0063] This invention improves the structure of existing WAT TSK PADs by changing large-area solid PADs to a mesh-like interlaced structure, avoiding continuous Cu dishing problems in subsequent process (BEOL) metal, ensuring the accuracy of WAT testing, and reducing the risk of bonding failure.
[0064] In the method of this invention, replacing the existing old PAD with a new WAT PAD solves the following problems: 1. WAT test reliability: The hollow mesh PAD structure of this invention replaces the existing solid PAD structure, which solves the dishing problem after CMP, reduces the contact resistance in WAT testing, and ensures the stability of WAT testing.
[0065] 2. Subsequent process compatibility: The hollow mesh PAD structure of this invention replaces the existing solid PAD structure, which solves the dishing problem after CMP and improves the reliability of the bonding structure.
[0066] In the method of this embodiment of the invention, on an existing WAT TSK, the PAD cells of the existing initial layout are replaced (switch) with the PAD cells of this embodiment of the invention. Next, an LVL comparison was performed using the raw data corresponding to the initial layout and the data after the switch cell replacement to confirm whether replacing the PAD cell affected other structures. Then, a new WAT TSK is obtained by performing a replacement GDS data run dummy insert.
[0067] The present invention has been described in detail above through specific embodiments, but these are not intended to limit the invention. Many modifications and improvements can be made by those skilled in the art without departing from the principles of the invention, and these should also be considered within the scope of protection of the present invention.
Claims
1. A test key pad structure, characterized in that: The test key pad is formed in a blocky structure. Within the forming area of the test key pad, the test key pad has a mesh-like interlaced structure. The mesh-like interlaced structure divides the metal within the forming area of the test key pad into multiple interconnected metal segment patterns. The width of each metal segment pattern is smaller than the width of the block structure, and the width of each metal segment pattern is set to meet the requirement that the metal of the test key pad does not undergo butterfly-shaped indentation.
2. The test key structure as described in claim 1, characterized in that: The mesh-like interlaced structure is defined by the layout pattern of the test key pads, which includes: A first pattern array formed by multiple parallel arrangement of first stripes extending in a first direction; A second pattern array formed by multiple parallel stripes extending in a second direction; The first direction and the second direction are perpendicular, and the mesh-like interlaced structure is formed by the intersection of the first pattern array and the second pattern array. Each of the metal segmentation patterns is composed of the corresponding first strip or the second strip.
3. The test key structure as described in claim 2, characterized in that: An interlayer film is formed in the regions between each of the metal segmentation patterns.
4. The test key structure as described in claim 3, characterized in that: The metal in each of the aforementioned metal segmentation patterns includes copper.
5. The test key structure as described in claim 2, characterized in that: The top view of the block structure is square.
6. The test key structure as described in claim 5, characterized in that: The width of each of the first strips is the same as the width of each of the second strips, and the spacing between each of the first strips is the same as the spacing between each of the second strips.
7. The test key structure as described in claim 6, characterized in that: The periphery of the interwoven mesh structure also has a metal ring structure; Both ends of each of the first strips and each of the second strips are connected to the metal ring structure.
8. A layout design method for a test key pad, characterized in that, include: The forming area of the test key pad is a block structure. The layout pattern of the test key pad is defined in the layout. The layout pattern of the test key pad has a mesh-like interlaced structure. The mesh-like interlaced structure is located in the forming area of the test key pad. The mesh-like interlaced structure divides the metal in the forming area of the test key pad into multiple interconnected metal segmentation patterns. The test key pad is fabricated according to the layout definition. Metal is formed at each of the metal segmentation patterns of the test key pad, and an interlayer film is formed between each of the metal segmentation patterns. The process of forming the test key pad also includes CMP to planarize the surface of the metal of the test key pad and the interlayer film outside the metal. The width of each metal segmentation pattern is smaller than the width of the block structure, and the width of each metal segmentation pattern is sufficient to prevent the metal of the test key pad from developing a butterfly-shaped depression during the CMP process.
9. The layout design method for the test key pad as described in claim 8, characterized in that: In the layout, the layout pattern of the test key pad includes: A first pattern array formed by multiple parallel arrangement of first stripes extending in a first direction; A second pattern array formed by multiple parallel stripes extending in a second direction; The first direction and the second direction are perpendicular, and the mesh-like interlaced structure is formed by the intersection of the first pattern array and the second pattern array. Each of the metal segmentation patterns is formed by the intersection of the corresponding first stripe and the second stripe.
10. The layout design method for the test key pad as described in claim 9, characterized in that: The metal in each of the aforementioned metal segmentation patterns includes copper.
11. The layout design method for the test key pad as described in claim 9, characterized in that: The top view of the block structure is square.
12. The layout design method for the test key pad as described in claim 11, characterized in that: The width of each of the first strips is the same as the width of each of the second strips, and the spacing between each of the first strips is the same as the spacing between each of the second strips.
13. The layout design method for the test key pad as described in claim 12, characterized in that: The periphery of the interwoven mesh structure also has a metal ring structure; Both ends of each of the first strips and each of the second strips are connected to the metal ring structure.
14. The layout design method for the test key pad as described in claim 9, characterized in that, Also includes: An initial layout is provided, wherein the formation area of the test key pad has a solid block-shaped structure pattern; The layout is obtained by replacing the pattern of the test key pad with the pattern of the test key pad having the mesh interlaced structure. This includes replacing the initial layout pattern of the test key pad having the solid block structure pattern in the initial layout with the pattern of the test key pad having the mesh interlaced structure.
15. The layout design method for the test key pad as described in claim 14, characterized in that, After the graphic replacement is completed, the method further includes: performing an LVL comparison on the data of the layout and the initial layout.